Colorado’s monsoon season will get a boost this week from Hurricane Polo, which is hitting the Mexican states of Sonora and Chihuahua Monday. An existing storm will be amplified in the West when it combines with remnants of what was a Category 5 hurricane that formed off the Pacific coast of Mexico.
The National Weather Service has issued a flood watch for much of southern and south central Colorado starting Tuesday, warning that some areas could get up to three inches of rain.
David Barjenbruch, a meteorologist with the NWS in Boulder, expects the strongest activity east of Denver and south of the Palmer Divide, including the San Luis Valley and much of southern Colorado, which may see up to five or six inches. The Denver metro will likely see lighter or moderate rains as the storms roll through the state starting Monday, and linger through Thursday.
“We’re watching this next approaching storm system very carefully, as it does carry the potential of flooding for much of Colorado,” Barjenbruch said.
Barjenbruch, however, said there is still a lot of uncertainty around which areas will get the heaviest rain. The rainfall rate itself may not be very high but could last for days.
“It’s one of those storms where if it stalls and slows down enough…you’re going to get some very heavy rain and we’ll have some flooding impacts,” Barjenbruch said.
Rainfall may bring some relief to the ongoing drought in Colorado. However, too much rain on very dry ground could result in flooding rather than breaking the drought.
The most drought-stricken western portions of the state will likely not see as much precipitation. But as the storms roll through the southwest on Monday, the region is under a flood watch and the San Juan mountains have a high flood threat, according to the state water conservation board’s Flood Threat Bulletin.
Low-lying areas with larger streams are at the highest risk of flooding. Regions with burn scars could also potentially see flash flooding — the Aspen Acres burn area is under moderate flood threat.
Rain should taper off on Thursday as the storm moves further east.
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